Debate: Mechanical vs Passive Strategies

The stage was set for rowdy debate of the tensions between mechanical and passive green building techniques at the recent Congress of the New Urbansim. Steve Mouzon, designer and author of The Original Green, Bill Browning of Terrapin Bright Green, Ann Daigle of the Princes Foundation, and Daniel Sloan of McGuire Woods, moderated by Elizabeth Plater-Zyberk, a founder of CNU, principal of DPZ and Dean of the University of Miami School of Architecture.

The dialogue began with inquiring on the premise of, will we be able to invent ourselves out of problems without causing more? For example the fluorescent bulb replacing the incandescent created a toxic waste problem with mercury, while helping our energy efficiency problem.

Steve Mouzon outlined a fundamental issue with additive rating systems such as LEED, in that it creates a mentality that more is better while teams are adding systems to gain points. Instead shouldn’t we be rewarded for frugality? We should in fact work to condition people better to live in various climates more than conditioning our buildings all to 72 degrees. Mouzon also added there needs to be a stronger emphasis on preservation and re-use. Why use material with recycled content when you can re-use materials?

Ann Diagle put some of Mouzon’s examples into action discussing projects supported by the Princes Foundation which implemented a full array of passive strategies. Currently one of the Princes Foundation’s is working on the “Natural House” [PDF] with a goal to reach for zero carbon living.

Bill Browning brought the conversation to a larger and commercial scale describing lauded green building projects such as the Bank of America tower in NYC or NREL’s new headquarters in Colorado, the most energy efficient office building to date. Given the scale, use, and demand of these projects, mechanical solutions were required. However, as the cost of energy continues to rise, how would skyscraper operations be effected with reliance on elevators and no operable windows? Newer projects are now including mixed-mode capability to rely on passive solutions part of the year.

Daniel Sloan focused back on the residential scale and argued that in order to maintain the quality of life the market demands, mechanical strategies will continue to be needed. He pointed out that we also need to be moving towards regenerate buildings to help repair what we have done to the world already.

So what’s the answer to this debate?

Both! The panel agreed that one should maximize passive strategies before implementing mechanical ones. Focus on orientation, site, and envelope before thinking about systems. Prioritize passive strategies such as natural ventilation, day lighting, natural materials, and increased insulation. However, to put an end to the debate we settled on something everything agrees with; there is a bit of a timeline to deal with the problems we are facing.